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Yang Nan Wei Xu Kyaw Zaw Kathrine E. Hughes Liang-Fu Huang William J. Dunn Ludwig Bauer Hemendra N. Bhargava 《Journal of heterocyclic chemistry》1997,34(4):1195-1203
Fusion of an azole moiety at C-6 and C-7 of naltrexone ( 1 ) is illustrated by the synthesis of the title compound 8 . Bromination of 3-O-methylnaltrexone led to the 1,7α-dibromo derivative which reacted with thiourea to attach the 2-aminothiazole ring to C-6 and C-7 of naltrexone. After converting the amino and alcohol groups to trimethylsilyl derivatives, the aromatic bromo group was removed by halo-lithium interchange with butyllithium, followed by hydrolysis with water. In the final step of the synthesis, the methyl ether was cleaved by boron tribromide to generate 8 . An alternate synthesis of 8 commenced with 3-O-acetylnaltrexone ( 9 ). Bromination of 9 in acetic acid in the presence of hydrobromic acid produced a mixture of 3-O-acetyl-7α-bromonaltrexone ( 10 ) and 7α-bromonaltrexone ( 11 ), both, as hydrobromides. Reaction of this mixture with thiourea furnished 8 (62% from 1 ). While 1H and 13C chemical shifts of all compounds are reported, those of 11 hydrobromide and 8 dihydrochloride were established unequivocally. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(39):11959-11963
The first asymmetric synthesis of important α,α‐disubstituted N‐alkyl allyl amine scaffolds through allylic substitution is reported. This approach is based on palladium catalysis and features ample scope with respect to both the allylic precursor and amine reagent, and high asymmetric induction with enantiomeric ratios (e.r.) up to 98.5:1.5. The use of less‐reactive anilines is also feasible, providing enantioenriched α,α‐disubstituted N‐aryl allylic amines. 相似文献
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Iridium‐Catalyzed Enantioselective Allylic Substitution of Unstabilized Enolates Derived from α,β‐Unsaturated Ketones 下载免费PDF全文
Ming Chen Prof. John F. Hartwig 《Angewandte Chemie (International ed. in English)》2014,53(33):8691-8695
We report Ir‐catalyzed, enantioselective allylic substitution reactions of unstabilized silyl enolates derived from α,β‐unsaturated ketones. Asymmetric allylic substitution of a variety of allylic carbonates with silyl enolates gave allylated products in 62–94 % yield with 90–98 % ee and >20:1 branched‐to‐linear selectivity. The synthetic utility of this method was illustrated by the short synthesis of an anticancer agent, TEI‐9826. 相似文献
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The catalytic activity of β‐cyclodextrin immobilized on Dowex resin as an efficient solid‐liquid phase transfer catalyst was developed for the synthesis of alkyl thiocyanates and phenacyl derivatives in water. The nucleophilic substitution reactions were performed under mild reaction condition and gave the products in excellent yields. Furthermore, the catalyst could be recycled by facile separation without any loss of activity. 相似文献
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Oleg V. Gusev Tat'yana A. Peganova Mikhail G. Peterleitner Svetlana M. Peregudova Larisa I. Denisovich Nikolai A. Ustynyuk
Peter M. Maitlis
《Journal of organometallic chemistry》1994,480(1-2):c16-c17Reaction of [Pt2(η5-C5Me5)2(η-Br)3]3+(Br−)3 with C5R5H (R = H,Me) in the presence of AgBF4 gives the first platinocenium dications, [Pt(η5-C5Me5)(η5-C5R5)]2+(BF4− )2. On electrochemical reduction, [pt(η5-C5Me5)2]2+ yields [Pt(η4-C5Me5H)(η2-C5Me5)]+ BF4−. kw]Cyclopentadienyl; Metallocenes; Platinum; Electrochemistry 相似文献